Efficient differential charge pump with sense and common mode control

A system, comprising:

• a phase detector configured to generate a first output signal related to a difference in phase between a received reference signal and a received feedback signal;
• a filter circuit;
• a variable frequency oscillator configured to generate a second output signal, wherein the feedback signal received by the phase detector is based on the second output signal;
• and
• a differential charge pump circuit configured to generate a signal across the filter circuit that is based on the first output signal, the differential charge pump circuit comprising:
• a reference current;
• a first sensing operational amplifier;
• a controlling operational amplifier;
• and
• an h-bridge circuit coupled to the reference current and the controlling operational amplifier, wherein the reference current drives a first portion of the h-bridge circuit and the controlling operational amplifier controls a second portion of the h-bridge circuit, the h-bridge circuit comprising:
• a first node;
• and
• a second node, wherein the first and second node are inputs to the first sensing operational amplifier, and wherein the h-bridge circuit is configured to control a voltage at the first node using the first sensing operational amplifier and a first transistor coupled to the first sensing operational amplifier, so that the voltage at the first node is substantially equal to a voltage at the second node for a plurality of voltages at the second node.

A differential charge pump circuit, comprising:

• a first sensing operational amplifier;
• and
• an h-bridge circuit, comprising:
• a first node;
• a second node, wherein the first and second nodes are inputs to the first sensing operational amplifier, and wherein the differential charge pump circuit is configured to control a voltage at the first node;
• and
• a first transistor coupled to the first node and the second node, the first transistor comprising a gate coupled to an output of the first sensing operational amplifier, wherein the voltage at the first node is controlled using the first sensing operational amplifier and the first transistor so that it the voltage at the first node is substantially equal to a voltage at the second node for a plurality of voltages at the second node.

A differential charge pump circuit, comprising:

• a first independent current source;
• a second independent current source;
• a first sensing operational amplifier;
• and
• an h-bridge circuit coupled to the first and second independent current sources, wherein the first independent current source drives a first portion of the h-bridge circuit and the second independent current source drives a second portion of the h-bridge circuit, the h-bridge circuit further comprising:
• a first node;
• a second node, wherein the first and second node are inputs to the first sensing operational amplifier, and wherein the circuit is configured to control a voltage at the first node using the first sensing operational amplifier and a first transistor coupled to the first sensing operational amplifier so that the voltage at the first node is substantially equal to a voltage at the second node for a plurality of voltages at the second node.

A phase-locked loop circuit, comprising:

• a phase detector configured to generate a first output signal related to a difference in phase between a received reference signal and a received feedback signal;
• a filter circuit;
• a variable frequency oscillator configured to generate a second output signal, wherein the feedback signal received by the phase detector is based on the second output signal;
• and
• a differential charge pump circuit configured to generate a signal across the filter circuit that is based on the first output signal, the differential charge pump circuit comprising:
• a first sensing operational amplifier;
• and
• an h-bridge circuit, comprising:
• a first node;
• a second node, wherein the first and second nodes are inputs to the first sensing operational amplifier, and wherein the differential charge pump circuit is configured to control a voltage at the first node;
• and
• a first transistor coupled to the first node and the second node, the first transistor comprising a gate coupled to an output of the first sensing operational amplifier, wherein the voltage at the first node is controlled using the first sensing operational amplifier and the first transistor so that it the voltage at the first node is substantially equal to a voltage at the second node for a plurality of voltages at the second node.